Catheters have found widespread use in medical procedures, such as percutaneous transluminal coronary angioplasty (PTCA) or for delivery of an implant such as a stent, a stent-graft or an occlusion device. Most catheters are guided to the application site by sliding the catheter along a guide wire, which has been carefully advanced and arranged within the patient. During advancement of the catheter along the guide wire, it is important to keep the guide wire steady. Ordinary catheters are guided to the application site in a patient by sliding the catheter along a guide wire extending all the way through a lumen of the catheter from the proximal end to the distal end thereof. To enable the physician to hold or manipulate the guide wire during advancement of the catheter along the guide wire, it has been necessary to have an excess length of guide wire. The guide wire must hence have a length of about twice the length of the catheter, e.g. 3 m in total, which greatly complicates the procedure.
An important sub-category of catheters includes catheters of the so-called rapid exchange type, which greatly facilitate operation, especially exchange of catheters if it is found during a procedure that a different kind or size of catheter is needed for a specific purpose. In the rapid exchange catheter, the guide wire only passes through a minor part of the catheter at the distal end thereof, whereas along a majority of the catheter, the guide wire runs in parallel with the catheter. Hence it is not necessary to have an excess length of guide wire. However, the rapid exchange catheter presents some challenges, especially with regard to resistance to kinking of the catheter.
An important feature of catheters is the transmission of force, the so-called push force, from the proximal end to the distal end of the catheter. This transmission significantly affects the physician's ability to direct the distal end of the catheter into a body lumen of a patient by manipulating the proximal end thereof. Another important feature of catheters is the flexibility of the distal end to bend and conform to the body lumen wall without causing any injury to the lumen wall. Hence catheters, especially of the rapid exchange type, are commonly manufactured of a metal proximal shaft portion of relatively high stiffness and known as a “hypotube”, and a relatively flexible plastics distal portion bonded to the hypotube. An abrupt change of properties between the hypotube and the distal portion, however, increases the risk of twist and kinking. Hence it is desirable to provide a good and simple transition between the relatively stiff hypotube to the relatively more flexible distal section to provide a sufficient resistance to twist and kinking while maintaining flexibility and ability to bend.
U.S. Pat. No. 6,635,029, U.S. Pat. No. 6,066,114, U.S. Pat. No. 7,273,470, and U.S. Pat. No. 7,297,134 disclose examples of rapid exchange catheters.
EP 0875263, US 2005/0177043, US 2004/0019324, WO 2008/005706, U.S. Pat. No. 5,549,552, WO 2008/134382 and WO 2007/059281 disclose deployment arrangements with tapered components, especially tapered distal tubes.